Centrifugal separator bowl having nozzles for continuous discharge of separated solids



CENTRIFUGAL SEPARATOR B ING NOZZLES CONTINUOUS DISCHARGE SEFARATED SOLID Filed May 12, 1951 Sept. 27, 1955 G. J. STREZY Kl FOR 2,719,003

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United States Patent CENTRIFUGAL SEPARATOR BOWL HAVING NOZZLES FOR CONTINUOUS DISCHARGE 0F SEPARATED SOLIDS George J. Strezynski, Poughkeepsie, N. Y., assignor to The De Laval Separator Company, New York, N. Y., a corporation of New Jersey Application May 12, 1951, Serial No. 225,986

4 Claims. (Cl. 23347) This invention relates to centrifugal separator bowls and, in particular, to such bowls of the type in which relatively heavy solids separated in the centrifugal bowl are discharged continuously through the peripheral portion of the bowl.

In the use of centrifugal separators of this type, as disclosed, for example, by Strezynski Patent No. 2,410,313, dated October 29, 1946, it is obvious that sufficient liquid or fluid must flow through the peripheral escape passages to carry out the solids. The amount of this liquid accompanying the solids, to effect their discharge, must be taken into consideration in determining the size of the peripheral escape passages. The range of particle size of the solids and the degree of packing thereof within the bowl must also be considered in the determination of the passage size.

It is known that by decreasing the size (through-flow area) of these peripheral escape passages, the dryness of the discharging solids is increased. On the other hand, the extent to which the size of these passages can be decreased is limited by the tendency of the discharging solids to clog the passages, which increases as the passages are made smaller. Such clogging interferes with the centrifuging operation and must be avoided. Consequently, it has been necessary in many instances to discharge the solids with a much higher liquid content than is desired, in order to enable the centrifuge to operate continuously Without danger of clogging.

The present invention has for its principal object the provision of an improved centrifugal separator bowl of the character described, which is adapted to eifect a continuous discharge of separated solids having a high degree of dryness, without danger of clogging the peripheral escape passages for the solids.

A separator bowl made according to the invention has in its peripheral portion a nozzle body through which the separated solids are discharged from the separating chamber in the bowl. Within the body of the nozzle is a chamber or space of substantial size. A restricted passage, of small through-flow area in relation to this space, is arranged in the nozzle body to connect the peripheral portion of the separating chamber of the bowl with the space within the nozzle body. A second restricted passage, likewise of small through-flow area in relation to this space, is arranged in the nozzle body to connect the space to the exterior of the bowl wall. In this way, a drop in pressure of the discharging solids is effected through the restricted passage leading from the periphery of the separating chamber of the centrifugal bowl to the space within the nozzle body in the bowl wall; and a further drop in pressure of the discharging solids is effected when they pass from the space within the nozzle body through the second restricted passage to the exterior of the bowl. Due to the cumulative effect of these multiple pressure drops in the nozzle body, the discharge through the nozzle body occurs at a much lower rate than is the case with an ordinary nozzle having the same through-flow area as either of the re- 2,719,003 Patented Sept. 27, 1955 stricted passages in the nozzle body. Thus, the new centrifugal bowl discharges the solids at a relatively low rate corresponding to the discharge rate afforded by a considerably smaller passage in a conventional nozzle type of bowl, without the clogging disadvantage attending the use of the smaller passage. The space within the nozzle body is preferably sealed except for the aforementioned restricted passages leading to and from it.

For a more complete understanding of the invention, reference may be had to the accompanying drawing, in which:

Figure 1 is a cross-sectional view of a preferred form of the new centrifuge bowl, showing only the outer portion of the bowl to which the nozzle body is applied, the view being taken on a horizontal plane through the mid-point of the nozzle body;

Figure 2 is a side elevational view taken along line 22 of Figure l and looking from within the separating chamber of the bowl; and

Figure 3 is a vertical sectional view on the line 33 of Figure 1.

In the drawing, the numeral 10 designates the centrifugal bowl, particularly its side or peripheral wall surrounding the usual separating chamber in the bowl. Equally spaced about the circumference of the bowl wall are several nozzle bodies, one of which is shown generally at 11. The sides of each nozzle body are tapered outward and are complementary to a frustro-conical seat 12 formed in the bowl wall 10 for receiving the nozzle body. A groove 13 extends around the nozzle periphery and contains a packing ring 14 which makes a tight joint between the nozzle body and the bowl wall.

The nozzle body is provided with a chamber or space 15 formed centrally within it and sealed except for restricted entrance and exit passages. In the illustrated embodiment, the chamber 15 is formed by the intersection of two bores 16 and 17, the former extending outward partially through the nozzle body from a point beginning adjacent the separating chamber of the bowl, and the latter extending completely through the body of the nozzle at an angle to the first bore. The open or inner end of bore 16 is sealed by a plug 18, while the inner and outer ends of bore 17 are fitted with bushings 19 having restricted through-flow passages 2t and 21, respectively.

The bore 17 extends generally tangentially relative to the annular bowl wall 10, its direction (from its inner end to its outer end) being opposite to the direction of rotation of the bowl, as indicated by the arrow A in Fig. 1. Accordingly, the solids escaping through the path 2015-21 in the nozzle body are discharged from the bowl in a backwardly reacting jet, thereby enabling a saving in the consumption of power necessary to drive the bowl. As shown, the outer surface of the bowl Wall has a recess 22 directly behind the outer, rear end of bore 17, so that it is not necessary for any part of the nozzle body to project beyond the contour of the bowl 10 in order to effect the discharge. It will be understood that the nozzle body is held by centrifugal force against its seat 12 during rotation of the bowl, so that the gasket or packing ring 14 forms a tight seal. When the bowl is stationary, the nozzle body is held in position by a retaining pin 23 which, however, can be adjusted or removed to permit withdrawal of the nozzle body from the bowl.

The nozzle 11 may be regarded as a nozzle holder, and the bushings 19 therein may be regarded as primary and secondary nozzles forming primary and secondary nozzle passages 20 and 21, respectively, interconnected in series by the relatively large sealed space 15. At the entrance to the primary nozzle passage 20, a high pressure prevails during operation of the bowl, due to the centrifugal force acting upon the body of liquid rotating in the separating chamber of the bowl. This pressure is many times greater than the pressure prevailing at the discharge end of the secondary nozzle passage 21, where the pressure generally is approximately atmospheric. Inv

the sealed space 15 between these two points, an intermediate fluid pressure prevails, which may be as low as one-half the pressure at the entrance to passage 20. Thus, the primary and secondary nozzles, and the intermediate sealed space 15, cause the fluid pressure to drop in two stages, instead of in a single stage, during the discharge through the nozzle holder. This has the effect of reducing considerably the discharge rate through the escape passage 2015--21, as compared with the rate through a conventional continuous escape passage of the same size (through-flow area) as the passages 20 and 21. This effect is due primarily to a substantial loss of pressure head caused by impact, eddying and turbulence at the region where the relatively small jet from passage 20 enters the relatively large and slower moving mass in the sealed space 15, and another substantial loss of pressure head caused by a somewhat similar action at the region where the space 15 joins the passage 21.

The new centrifugal bowl provides several advantages in the operation of centrifugal separators adapted for continuous discharge of separated solids. The main advantage stems from the fact that the discharge passage 20 15--21 provides a discharge rate corresponding to that of a considerably smaller discharge passage of conventional form in such centrifuges. The ever present danger of the passage plugging is materially decreased as a result, since the passage can be made larger than in conventional bowls, without a corresponding decrease in the dryness of the discharging solids. Also, fewer nozzles may be used while maintaining the same rate of discharge of the solids. This results in the solid particles having to travel farther about the periphery of the separating chamber to find an escape path, so that they are subjected to the maximum centrifugal force for a longer time and thereby attain a higher degree of dryness and/or solids concentration.

I claim:

1. In a centrifugal bowl having a separating chamber and a peripheral wall surrounding the chamber, said wall having an opening for discharge of separated solids from the outer portion of the chamber, the combination of a nozzle holder in said opening, the holder having a passageway adapted to receive nozzles extending continuously outward therethrough from the outer portion of the separating chamber to the outside of the peripheral wall, and a pair of solids discharge nozzles serially connected in the passageway to form therewith an outlet path for the solids extending from said outer portion of the chamber to the outside of said wall, the nozzles including a primary discharge nozzle in the inner portion of said passageway and having a restricted passage leading from said outer portion of the separating chamber, and a secondary discharge nozzle substantially similar to and receiving solids discharged from the primary nozzle, the secondary nozzle being located in the outer portion of the passageway and having a restricted passage leading to the outside of said wall, the nozzles defining between them an enlarged space in the passageway interconnecting said restricted passages, said passages being of small through-flow area as compared with said interconnecting space.

2. A combination according to claim 1, in which said space in the nozzle holder is sealed except for said passages leading to and from it.

3. A combination according to claim 1, in which the nozzle holder also has a second passageway extending only partly therethrough from the separating chamber and intersecting the first passageway between said nozzles, to form said enlarged space.

4. A combination according to claim 1, in which the nozzle holder also has a second passageway extending only partly therethrough from the separating chamber and intersecting the first passageway between said nozzles, to form said enlarged space, and a plug closing the inner end of said second passageway, the first bore being sealed except for said restricted passages.

References Cited in the file of this patent UNITED STATES PATENTS 1,279,287 Davies Sept. 17, 1918 1,793,204 Altpeter Feb. 17, 1931 1,970,552 Berge Aug. 21, 1934 2,410,313 Strezynski Oct. 29, 1946 FOREIGN PATENTS 75,743 Sweden Oct. 30, 1931 387.298 Great Britain Feb. 2. 1933 

